The present invention generally relates to a guiding catheter and method for making the same, and more particularly to a guiding catheter that has a lubricious lumen and that is thin-walled while still exhibiting excellent strength characteristics, the thin-walled construction being one in which the elongated body of the catheter includes a thin flexible outer sheath that overlies a thin rigid intermediate sheath which in turn overlies a third, interior sheath that provides the lubricious lumen. The guiding catheter further includes a flexible, atraumatic tip portion located at one end of the elongated tubular member, which tip portion has a structure similar to the elongated body portion but which does not include the rigid intermediate layer.
Guiding catheters are well-known for use in diagnostic and therapeutic applications wherein they are used to provide a guiding lumen through which a treating catheter such as an intravascular catheter or the like is passed such that the treating catheter may be used to administer a fluid to, or otherwise contact such as with a balloon, a precise location within the cardiovascular system. In order to accomplish this, the guiding catheter must be able to traverse a pathway through, for example, branching blood vessels. Prior to insertion of the treating catheter through the guiding lumen of the guiding catheter, the guiding catheter is positioned in the vicinity of the administration or treatment location, this positioning being accomplished in part by manipulation of a proximal portion of the guiding catheter in order to impart forces needed to curve and guide the guiding catheter through the curving and branching blood vessels, at times in association with a very small diameter elongated flexible guide wire.
Typical assemblies including a guiding catheter and a treating catheter are assemblies used for percutaneous transluminal coronary angioplasty. In such systems or assemblies, it is important that the guiding catheter, as well as the treating catheter, exhibit adequate torque control while at the same time having a substantially atraumatic tip. One such guiding catheter structure is made by extruding a thin base coat of a polyfluoroethylene, such as Teflon materials available from E.I. duPont de Nemours & Co., Inc., over a mandrel, after which a braided material, which may be metal wire, is positioned thereover, and coated with a flexible material. Braided guiding catheters of this type do not always provide the exceptional degree of torque control that is desired for guiding catheters of the intravascular type, and they may also exhibit a somewhat excessively stiff tip portion. Good torque control is exhibited when slow rotation of the hub end of a catheter is translated to the tip or distal end without "whipping", which is characterized by a temporary lag in movement followed by a rapid rotation.
Other guiding catheters that are especially useful in assemblies for percutaneous transluminal recanalization of chronic arterioschlerotic obstructions by catheterization techniques are of structure that includes an inner hose having a surface layer of synthetic fiber fabric such as a Nylon (duPont trademark) polyamide, which is covered by a protective hose of a material such as a fluoroethylenepropylene that is heat shrunk therearound. Another guiding catheter provides a tetrafluoroethylene polymer tubular member that is encased within a heat shrunk flexible tubular member made of a modified polyolefin.
Because these guiding catheters are used in an intravascular manner, they must have an extremely small outside diameter, while still providing an inside diameter or lumen size that is adequate to permit the passage of the treating catheter therethrough. Furthermore, since these catheters come into contact with living tissue, including organs such as the heart, it is extremely important that the guiding catheter be in place for a minimal length of time. Overall insertion time includes the length of time needed to feed the guiding catheter through a cardiovascular system and then feed the treating catheter through the lubricious lumen of the guiding catheter. Such insertion time can be better controlled if the guiding catheter is stiff enough to be resistant to the formation of kinks therein, while at the same time possessing enough flexibility to be responsive to maneuvering forces and to provide adequate torque control when the guiding catheter is manipulated in conjunction with feeding same through a somewhat tortuous path. At the same time, the guiding catheter, particularly its distal end or tip portion, should be as atraumatic as possible.
The present invention provides a guiding catheter that meets these needs and objectives by virtue of its having a multi-layered structure which includes an innermost layer of a highly lubricious material, onto which is coated a thin, rigid intermediate layer which exhibits strength and stiffness properties that are extremely advantageous for an intravascular guiding catheter while still having adequate flexibility in its thin-walled sheath condition to permit the flexibility required of such a catheter. Closely overlying, and typically extruded onto, the rigid intermediate sheath is a flexible, thin-walled outer sheath that is compatible with the intermediate sheath and that, as a layer over the rigid intermediate sheath, imparts improved atraumatic properties to the longitudinal extent of the catheter and contributes to the overall flexibility of the guiding catheter, while also providing convenient opportunities to impart radiopaque properties to the catheter. While these guiding catheters may be produced such that a separate tip member is secured to the distal end of the body of the guiding catheter, it is preferred that the guiding catheter be structured in a manner such that the interior, lubricious sheath is an integral, one-piece continuous sheath that extends through both the body portion and the tip portion.
It is accordingly a general object of the present invention to provide an improved guiding catheter that is particularly well-suited for intravascular uses.
Another object of the present invention is to provide a thin-walled, multi-layered catheter that is especially suitable for use as a guiding catheter in conjunction with highly delicate treatments and diagnostic procedures including coronary angiography, coronary angioplasty, ventricular and/or aortic flush injections, and other similar procedures within the cardiovascular system.
Another object of this invention is to provide an improved thin-walled guiding catheter and method of making same which include positioning a highly lubricious lumen within a guiding catheter exhibiting excellent torque control. Another object of the present invention is to provide an improved guiding catheter and method by which the body portion and the tip portion thereof share a continuous, one-piece lubricious interior sheath.
Another object of the present invention is to provide an improved thin-walled guiding catheter that has a multi-layered construction of extruded material and that does not require adding any braiding or strands of strengthening material therebetween.
Another object of this invention is the utilization of a relatively rigid material in a thin-walled form within an elongated guiding catheter suitable for intravascular uses.
Another object of the present invention is to provide an improved intravascular guiding catheter that exhibits excellent torque response or control and that is particularly resistant to kinking, while still possessing the atraumatic properties and thinness needed for an intravascular catheter.
These and other objects, features and advantages of this invention will be clearly understood through a consideration of the following detailed description.